Explosion-proof switch housing



April 4, 1944. R LESTER 2,345,757

EXPLOSION PROOF SWITCH HOUSING Filed Feb. 2, 1940 5 Sheets-Sheet l BYiff/Zw MW ATTORNEYS.

April 4, 1944. R F LESTER 2,345,757

EXPLOSION PROOF SWITCH HOUSING Filek-Feb. 2, 1940 3 Sheets-Sheet 2 j? lNVENTOR. @-4- Qjm l f ATTORNEYS.

April 4, 1944.

R. F. LESTER 2,345,757

EXPLOSION PROOF SWITCH HOUSING O HO 55 Ki? ATTORNYS Patented Apr. 4,1944 PATENT OFFICE EXPLOSION ZIROOI" SWITCH HOUSING Bay F.'Lester,Syracuse, N. Y.. Hinds Company, Syracuse,

vtion of New York assigner to Crouse. N. Y., a corpora- AppucauonFebruary z, loro, semi No. 311,022

2 Claims. This invention relates to switch lhousings designated as theexplosion proof type employed to house switches and other electricalapparatus in hazardous locations.

The embodiment of the invention here shown is intended particularly foruse in hospital operating rooms where there is likely to be presentether, or other inammable vapors. The structureherein referred to isintended to be mounted in the wall of the'operating room near `oradiacent the floor, and involves a particularly durable structurepermitting the switch to be operated by the foot to avoid the necessityof the surgeons, and operating room attendants, operating the switchmanually by hand. It Vis desirable in mounting switches in suchlocations that the exposed surface of the switch be of attractive iinishand be properly mounted so that the cover member of the switch isproperly tted against the wall of the room.

'I'he invention has as an object a switch housing of the type refened toembodying a structure by which the body of the housing may be installedin the wall structure and connected in the conduit system during theconstruction of the building, a cover member in which the switchactuating mechanism is mounted, and an intermediate member carried bythe body and in which the switch is mounted, the intermediate memberbeing adjustable toward and from the surface of the wall so that thecover member is properly mounted on the finished wall surface of theroom in a neat and attractive manner.

The invention has ,as a further object a switch housing of the typereferred to embodying a structure effecting an efllcient flame-tightjoint between the cover member and the intermediate member. l

A further object of the invention-is a switch housing embodying astructure whereby the elements -subsequently installed on the body ofthe fitting and which enclose the switch may be properly sealed as aflame-tight unit-,at the factory with the leads from the switch, orother apparatus, mounted in the housing extending from said unit forconnection within the body member to the conductors in the conduitsystem, and the unit quickly and conveniently installed in the body,,whereby the complete housing forms a tight explosion proof enclosurefor the apparatus mounted therein.

The invention consists in the novel features and in the combinations andconstructions herein after set forth and claimed.

In ldescribing this invention, reference is had (Cl. 20o-168) to theaccompanying drawings in which like characters designate correspondingparts in all the views.

Figure 1v is a top plan view of a switch housing 5 embodying myinvention.

Figure 2 is a sectional view taken on line 2 2, Figure 1.

Figure 3 is a top plan view of a switch housing generally similar tothat shown in Figures 1 and 2 embodying the modified mounting for theswitch and a thermostatic actuating mechanism.

Figure 4 is a. view taken on line 4-4, Figure 3. Figure 5 is a top planview of a modified form the switch housing shown in Figures 1 and 2.Figure 6 is a sectional view taken on line 6 6, Figure 5.

The invention consists oi.'v a body member in the nature of a conduitoutlet box which may be installed in the wall structure and connected inthe conduit system. A sleeve is threaded into the outlet boilr and acover member secured to the outer end of the sleeve. The sleeve isthreaded into the box to provide adjustment of the cover member toproperly position the same against the wall surface. The switch ismounted within the sleeve member and is actuated to on and od positionby switch operating mechanism mounted in the cover member. Theconstruction is such that the body, sleeve, and cover member, form anexplosion proof housing for the switch. If it is desired to have theswitch housing effectively sealed from the conduit system, the inventionfurther contemplates a cup shaped member arranged in the sleeveembodying a structure whereby the wires connected to the switch aresealed in the bottom of the cup-shaped member and the cover forming a.dame-tight or explosion prooi closure for the open end of the cup shapedmember.

The body I may be of any desired form, it being here shown as ofcircular formation and provided with a pluralityof radially extendinghub members II provided with an internally threaded passage I2 toreceive the ends of the conduits. The body I0 is provided at one side45, with an internally threaded opening into which an internallythreaded sleeve I3 is threaded. The sleeve I3 is formed at its outeredge with a radial flange I4 formed with a plurality of concentricannular shoulders I arranged in step formation.

In Figures 1 to 4, a cup shaped member I 6 is mounted within the sleeveI3 and is likewise formed with a radial flange I1 formed with anintermediate portion I8 extending in angular relationship to the axis ofthe cup shaped mem- 65 ber. Both the inner and outer sides of theintermediate portion 'I8 is formed with'a plurality of concentricallyarranged annular shoulders, i

extending through thebottom of the member I6 may be connected to theconductors of the conduit systemand the unit comprising the cup shapedmember with the cover20 attached thereto inserted in or mounted upon thesleeve I3. as by screws 41.

'l This procedure avoids the necessity of the 'workman disrupting thejoint between the cup intermediate portion I8 of flange Il is formedwith a step formation 24 complemental to the step formation on the outersurface of the intermediate portion I8. The arrangement is such that thestep formation 24 of the cover member is also complemental to the stepformation I on sleeve I3. Where it is not necessary to seal off theinterior of the switch housing from the conduit system, the cover may bemounted directly on the sleeve I3, as illustrated in Figure 6.

In Figures 1 and 2, the switch 25 is carried by a supporting plate 26mounted on inwardly extending projections 21 formed on the cup shapedmember I6. The switch actuating mechanism is carried by the cover member20, the cover being formed with a boss 28 extending outwardly and at anangle to the axis of the housing and being formed with an aperture 29,the inner lportion of which is threaded to receive a bushing 30. Anoperating stem 3| is slidably mounted-in the bushing 30 and a button 32is secured to the outer end of the stem 3| land is slidably mounted inthe recess 29. The stem 3| and button 32 are urged outwardly by ahelical compression spring 33 encircling the stem and the outer end ofthe bushing 30. In Figures 5 and 6, the cover 2|) is provided with apair of operating buttons 32, and a pair of switches are mountedwithin'y the sleeve I3 on inwardly extending bosses 34.

In Figures 3 and 4, the cover 20 is of substantially fiat circularformation and is formed with a threaded aperture to receive a which isrotatably mounted a stem 36. A mercury tube switch 31. is secured tothelowerV end of the stem 36, and the stem is oscillated in the bushing 35by a thermostat mechanism indicated at 38 enclosed in a housing 39mountedupon the cover. 4

The bottom wall of the cup shaped member I8 is formed with one or moreapertures .to permit the passage of conductors 40 from the interior ofthe body I0 to the interior of the cup shaped member IB. These aperturesare formed in a transversely extending thickened portion 4| formed withinternal anges 42 at the top and bottom of each passage. After theconductors 4|) have been extended through the passages, the passages arefilled with a sealing medium 43 and the flanges 42 assist in holding thesealing mey dium in the passages. l Preferably, the leads 40 areextended through the passages in the bottom of the cup shaped member andthe leads sealed in said passages, the

switch 25, 31 installed, and the cover 20 secured to the flange I1, asby screws 46, all at the factory. To install the switch, itis onlynecessary for the workman to screw the sleeve I3 into the body I0 theproper distance to bring the flange 22 of the cover in close proximityto the nished wall surface 23. Thereafter, the ends of the leads 40busting ss in shaped member and the cover and disturbing the factoryseal aboutthe leads 43. The sleeve I3 provides a convenient means foradjusting the cover 20 to eifectproper mounting of the same relative toVthe'finished wall surface without in lany way twisting or otherwisedamaging the wiring connected to the switch. The angularly arranged stem3| with push button 32 forms a convenient and durable mechanismpermitting the switch to be operated by pressing the button 32 with thefoot.

What I claim is:

1. An explosion proof switch housing comprising a body for installationwithin the wall structure of a room and being formed with a conduitreceiving aperture and with anl opening in one side, a flame tightswitch enclosure comprising a cup shaped member and a cover detachablysecured in flame tight relation to the open end of said member andhaving a radially extending flange adapted to overlie the marginalportion about an opening in the wall structure, a switch mounted in saidenclosure, lead vconductors extending from the terminals of the switchthrough the wall of the enclosure into said body, switch operatingmechanism carried by the cover and being operable externally thereof tomove the switch into on and oiI positions, said conductors and theswitch operating mechanism being sealed in flame tight relation in saidenclosure, means for supporting said' enclosure in the opening of thebody in flame tight relation thereto, and said means being operable toadjust said enclosure toward and from the body to position the flange ofthe cover in contact with the wall surface.

2. An explosion proof switch housing comprising a body formed with aconduit receiving aperture and with an opening in one side, a sleevethreaded'into said opening and being formed at its outer end with anannular flange, a flame tight switch enclosure comprising a cup shapedmember arranged in said sleeve and having a radially exvtenciing ,angeoverlapping the ange on said sleeve, the confronting surfaces of theanges of said cup shaped member and sleeve being formed with a pluralityof complemental annular shoulders arranged instep formation, a switchmounted in said enclosure, lead conductors extending through the wall ofthe enclosure into said body, a cover detachably secured to the open endof said cup shaped member in flame tight relation thereto, switchoperating mechanism carried by the cover and being operable externallythereof to move the switch into on and olf positions, said conductorsand switch operating mechanism being sealed in ame tight relation insaid enclosure, said sleeve being of appreciable length and operable toadjust the enclosure toward and from the body, and means operable todetachably clamp the anges of said sleeve and cup shaped membertogether.

- RAY F. LESTER.

CERTIFICATE 0F CORRECTION. Patent No. 2,5LI5,757. April LI, 19th.

RAY F. LESTER.

It is hereby certified that error a ofthe above numbered patentrequiring ond column, line 11.6, for

ppear-s in the printed specification correction as follows: Page l,y:esec- "nternally" read -exteznallyvg and that the said Letters Patentshould be read with this correction therein that the same may confom tothe record of the case in the Patent Office.

signed and sealed this 50th day of May,'A. D. 19ML.

Leslie Frazer (Seal) Acting Commissioner of Patents.

CERTIFICATE oF CORRECTION. Patent No. 2,515,757. April u, 19ML.

RAY F. LESTER.

It is hereby Certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page l,ysecond column, line 146, for internally read "externally-j; and thatthe said Letters Patent 'should be read with this correction thereinthat the same may conform to the record of the case in the PatentOffice.

signed and sealed this 50th day of May,'A. D. 19th.

Leslie Frazer (Seal) Acting Commissioner of Patents.

